. Pre-heat the oven at 100 degree C for 5 minutes. Grease a 9×9 inch baking tray with a little oil, place a butter paper and keep it aside.
. Melt chocolate and butter in a bowl using a microwave or a double boiler. Mix to combine well.
. In another mixing bowl, whisk the eggs until light and fluffy. Add the sugar, a little at a time, and whisk well.
. Add the chocolate and butter mixture and combine well.
. Sift together the cocoa powder, buckwheat flour and baking powder. Add to the wet batter, one tablespoon at a time, and fold well.
. Toss the walnuts and cacao nibs in 1 tsp wheat flour.
. Pour the chocolate batter into the baking tray and throw in the walnuts and cacao nibs in between. Bake in the oven for 20 minutes at 150 degree C until firm on the outside. The inside will remain a little gooey.
. Remove from the oven, let it cool and cut into squares.